The present invention relates to a movable body driving apparatus for opening and closing a vehicle door or the like automatically.
Among conventional movable body driving apparatus of the above type, a door driving apparatus which uses a linear motor is known. JP-A-2000-142392 (page 6, FIG. 1) discloses a door opening/closing apparatus which opens and closes right and left doors using a single linear motor. FIG. 8 shows the configuration of a door opening/closing apparatus that is similar to the above one. As shown in FIG. 8, a movable member 101a of a linear motor 101 is connected to a left door 111 via hanging metal fittings 113a and 113b and a door drive plate 115.
A top rack 117 is fixed to a right door 112 via hanging metal fittings 114a and 114b and a link metal fitting 116, and a bottom rack 119 is in mesh with the top rack 117 via a pinion 118. The bottom rack 119 is connected to a link rod 120, and the link road 120 is connected to the movable member 101a of the linear motor 101 via the above-mentioned door drive plate 115.
When the movable member 101a is moved rightward or leftward (as viewed in FIG. 8), as the linear motor 101 is driven, the left door 111 and the right door 112 are slid in opposite directions and are thereby opened or closed.
FIGS. 9 and 10 show a conventional example in which a left door 111 and a right door 112 are opened and closed being driven by two linear motors 101 and 101′. As shown in FIGS. 9 and 10, a movable member 101a of a linear motor 101 is connected to the left door 111 via a door hanging metal fitting 113 and a lock hole bracket 121. Likewise, a movable member 101a′ of a linear motor 101′ is connected to the right door 112 via a door hanging metal fitting 113′ and a lock hole bracket 121′.
When the movable members 101a and 101a′ are moved in the right-left direction (see FIG. 9) in opposite directions as the linear motors 101 and 101′ are driven, the left door 111 and the right door 112 are opened or closed being guided by door rails 122 and 122′ (see FIG. 10).
Each of the conventional techniques of FIGS. 8-10 employ a linear motor(s) as a drive source. However, because of their structure, using linear motors, the length of a motor case (cylinder case) is equal to a door stroke length (in general, 600-900 mm) plus the length of the movable member. Therefore, linear motors are heavier and occupy a larger area than rotary motors.
Therefore, when employed in a vehicular door opening/closing apparatus, one or more linear motors is an obstacle to a compact design. Furthermore, where a permanent magnet movable coil type linear motor, for example, is used, there is another problem that the apparatus as a whole is costly because of the use of a large rare earth permanent magnet.
The present invention solves the above problems. An object of the invention is therefore to provide a movable body driving apparatus which enables a compact design and can simplify adjustment work after its mounting.
Further objects and advantages of the invention will be apparent from the following description of the invention.